linux-kernel - Re: [PATCH 2/2] perf tools: Fix find_perf_probe_point_from

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Message-ID: <20151105160000.GX13236@kernel.org>
Date:	Thu, 5 Nov 2015 13:00:00 -0300
From:	"acme@...nel.org" <acme@...nel.org>
To:	平松雅巳 / HIRAMATU，MASAMI 
	<masami.hiramatsu.pt@...achi.com>
Cc:	'Wang Nan' <wangnan0@...wei.com>,
	"namhyung@...nel.org" <namhyung@...nel.org>,
	"lizefan@...wei.com" <lizefan@...wei.com>,
	"pi3orama@....com" <pi3orama@....com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"jolsa@...nel.org" <jolsa@...nel.org>
Subject: Re: [PATCH 2/2] perf tools: Fix find_perf_probe_point_from_map()
 which incorrectly returns success

Em Thu, Nov 05, 2015 at 02:08:48PM +0000, 平松雅巳 / HIRAMATU，MASAMI escreveu:
> From: Wang Nan [mailto:wangnan0@...wei.com]
> >
> >It is possible that find_perf_probe_point_from_map() fails to find
> >symbol but still returns 0 because of an small error when coding:
> >find_perf_probe_point_from_map() set 'ret' to error code at first,
> >but also use it to hold return value of
> >kernel_get_symbol_address_by_name().
> 
> OK, I didn't expect that there is a symbol which can be found by 
> kernel_get_symbol_address_by_name() but not by __find_kernel_function()...

> Would you have any example of the error?
> 
> >
> >This patch resets 'ret' to error even kernel_get_symbol_address_by_name()
> >success, so if !sym, the whole function returns error correctly.
> 
> Hmm, that sounds tricky. I'd rather like to add *psym to kernel_get_symbol_address_by_name() 
> to save symbol and don't use __find_kernel_function() instead.

Tricky? I don't think so, suboptimal? possibly, but it fixes an error,
so should be processed quickly, right? I'm applying his patch and then
whatever improvement can be done on top.

- Arnaldo
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